A conventional image forming device such as a laser printer includes a main casing, and within the main casing, a drum unit is detachably mounted. The drum unit includes a photosensitive drum, a developing cartridge retaining a developing roller, and a charger for uniformly charging a surface of the photosensitive drum. A scorotron charger having a charging wire and a grid electrode has been widely used as the charger.
While using the image forming device, dust such as paper dust are deposited on the charging wire. If dust is deposited on the charging wire, charging performance of the wire to charge the surface of the photosensitive drum is degraded. In order to prevent dust from being deposited on the charging wire, the charger includes a wire cleaner for cleaning the charging wire. The wire cleaner is moved along the charging wire, so that the charging wire can be cleaned.